Synthesis of (3) H, (2) H4 and (14) C-SCH 417690 (Vicriviroc)

Hydrogen Isotope Labeling of Pharmaceuticals Via Dual Hydrogen Isotope Exchange Pathways Using CdS Quantum Dot Photocatalyst

Isotopic labeling is a powerful technique extensively used in the pharmaceutical industry. By tracking isotope-labeled molecules, researchers gain unique and invaluable insights into the pharmacokinetics and pharmacodynamics of new drug candidates. Hydrogen isotope labeling is particularly important as hydrogen is ubiquitous in organic molecules in biological systems, and it can be introduced effectively through late-stage hydrogen isotope exchange (HIE). However, hydrogen isotope methods that simultaneously label multiple sites with varying types of C-H bonds in the different types of molecules are still lacking. Herein, we demonstrate a heterogeneous photocatalytic system using a CdS quantum dot catalyst that proceeds via a unique dual HIE pathway mechanism─one occurs in the reaction solution and the other on the catalytic surface─to address it. This unique mechanism unlocked several unique labeling capabilities, including simultaneous labeling of multiple and challenging sites such as secondary α-amino, α-ethereal, allyl, and vinyl sites, providing great versatility in practical uses for pharmaceutical labeling.

Automated radiosynthesis of the adenosine A2A receptor-targeting radiotracer [18 F]FLUDA

[¹⁸ F]FLUDA is a selective radiotracer for in vivo imaging of the adenosine A_2A receptor (A_2A R) by positron emission tomography (PET). Promising preclinical results obtained by neuroimaging of mice and piglets suggest the translation of [¹⁸ F]FLUDA to human PET studies. Thus, we report herein a remotely controlled automated radiosynthesis of [¹⁸ F]FLUDA using a GE TRACERlab FX2 N radiosynthesizer. The radiotracer was obtained by a one-pot two-step radiofluorination procedure with a radiochemical yield of 9 ± 1%, a radiochemical purity of ≥ 99% and molar activities in the range of 69-333 GBq/μmol at the end of synthesis within a total synthesis time of approx. 95 min (n = 16). Altogether, we successfully established a reliable and reproducible procedure for the automated production of [¹⁸ F]FLUDA.

Synthesis of 3 H, 13 C2 , 2 H414 C-SCH 430765 and 35 S-SCH 500946, potent and selective inhibitors of the NPY5 receptor

SCH 430765 and SCH 500496 are potent and selective antagonists of the NPY₅ receptor. NPY₅ receptor antagonists have the potential for the treatment of obesity. [³⁵ S]SCH 500946 was prepared for a competition binding assay which led to the identification of SCH 430765. Three distinct isotopically labelled forms of SCH 430765 were synthesized. [³ H]SCH 430765 was prepared for a preliminary absorption, distribution, metabolism and excretion data evaluation of the compound and [¹⁴ C]SCH 430765 for more definitive absorption, distribution, metabolism and excretion data work. In addition, [¹³ C₂ ,² H₄ ]SCH 430765 was prepared as an internal standard for a LC-MS bioanalytical method. The paper discusses the synthesis of 3 isotopically labelled forms of SCH 430765 and [³⁵ S]SCH 500946.

Synthesis of 3 H, 2 H4 , and 14 C-MK 3814 (preladenant)

MK 3814 is a potent and selective antagonist of the A_2a receptor. A_2a receptor antagonists have the potential for the treatment of Parkinson disease. Three distinct isotopically labelled forms of MK 3814 were synthesized. [³ H]MK 3814 was prepared for a preliminary absorption, distribution, metabolism, and excretion data (ADME) evaluation of the compound and [¹⁴ C]MK 3814 for more definitive ADME work, including an absorption, metabolism, and excretion study in man. In addition, [² H₄ ]MK 3814 was prepared as an internal standard for a liquid chromatography mass spectrometry bioanalytical method. This paper discusses the synthesis of 3 isotopically labelled forms of MK 3814.